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    Terroir Dynamics: Impact of Vineyard and Canopy Treatment with Chitosan on Anthocyanins, Phenolics, and Volatile and Sensory Profiles of Pinot Noir Wines from South Tyrol
    (MDPI (Basel, Switzerland), 2024-04-23) Tchouakeu Betnga PF; Poggesi S; Darnal A; Longo E; Rudari E; Boselli E; Rolle L
    The effects of canopy treatment with chitosan and the effects of the vineyard location on the quality parameters, volatile and non-volatile profiles, and sensory profile of Pinot Noir wines from South Tyrol (Italy) were studied. Multivariate statistical analysis was applied to identify the most relevant compounds associated with the variability in phenolics and anthocyanins (analyzed by UHPLC-MS), volatile components (HS-SPME-GCxGC-ToF/MS), and basic enological parameters. A clear separation of low-altitude wines (350 m.a.s.l.), which had a high concentration of most of the identified volatile compounds, compared to high-altitude wines (800 and 1050-1150 m.a.s.l.) was pointed out. Low altitude minimized the concentration of the most significant anthocyanins in wines from a valley bottom, presumably due to reduced sun exposure. Wines obtained from chitosan-treated canopies, and, more particularly, those subjected to multiple treatments per year showed a higher amount of the main non-volatile phenolics and were sensorially described as having "unpleasant flavors" and "odors", which might suggest that grape metabolism is slightly altered compared to untreated grapevines. Thus, optimization of the treatment with chitosan should be further investigated.
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    Cell Wall Carbohydrate Dynamics during the Differentiation of Infection Structures by the Apple Scab Fungus, Venturia inaequalis.
    (American Society for Microbiology, 2023-06-15) Rocafort M; Srivastava V; Bowen JK; Díaz-Moreno SM; Guo Y; Bulone V; Plummer KM; Sutherland PW; Anderson MA; Bradshaw RE; Mesarich CH; Wang Y
    Scab, caused by the biotrophic fungal pathogen Venturia inaequalis, is the most economically important disease of apples. During infection, V. inaequalis colonizes the subcuticular host environment, where it develops specialized infection structures called runner hyphae and stromata. These structures are thought to be involved in nutrient acquisition and effector (virulence factor) delivery, but also give rise to conidia that further the infection cycle. Despite their importance, very little is known about how these structures are differentiated. Likewise, nothing is known about how these structures are protected from host defenses or recognition by the host immune system. To better understand these processes, we first performed a glycosidic linkage analysis of sporulating tubular hyphae from V. inaequalis developed in culture. This analysis revealed that the V. inaequalis cell wall is mostly composed of glucans (44%) and mannans (37%), whereas chitin represents a much smaller proportion (4%). Next, we used transcriptomics and confocal laser scanning microscopy to provide insights into the cell wall carbohydrate composition of runner hyphae and stromata. These analyses revealed that, during subcuticular host colonization, genes of V. inaequalis putatively associated with the biosynthesis of immunogenic carbohydrates, such as chitin and β-1,6-glucan, are downregulated relative to growth in culture, while on the surface of runner hyphae and stromata, chitin is deacetylated to the less-immunogenic carbohydrate chitosan. These changes are anticipated to enable the subcuticular differentiation of runner hyphae and stromata by V. inaequalis, as well as to protect these structures from host defenses and recognition by the host immune system. IMPORTANCE Plant-pathogenic fungi are a major threat to food security. Among these are subcuticular pathogens, which often cause latent asymptomatic infections, making them difficult to control. A key feature of these pathogens is their ability to differentiate specialized subcuticular infection structures that, to date, remain largely understudied. This is typified by Venturia inaequalis, which causes scab, the most economically important disease of apples. In this study, we show that, during subcuticular host colonization, V. inaequalis downregulates genes associated with the biosynthesis of two immunogenic cell wall carbohydrates, chitin and β-1,6-glucan, and coats its subcuticular infection structures with a less-immunogenic carbohydrate, chitosan. These changes are anticipated to enable host colonization by V. inaequalis and provide a foundation for understanding subcuticular host colonization by other plant-pathogenic fungi. Such an understanding is important, as it may inform the development of novel control strategies against subcuticular plant-pathogenic fungi.
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    Stimuli sensitive polysaccharide based hydrogels as colon targeted drug delivery vehicles : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry, Massey University, Turitea campus, Palmerston North, New Zealand
    (Massey University, 2014) Kavianinia, Iman
    Administering drugs orally is by far the most widely used route of administration that will help eliminate the pain caused by injection, psychological barriers associated with multiple daily injections and possible infection from injection sites. However, it is important for oral drug administration to overcome several different obstacles during the delivery through the gastrointestinal tract. The barriers can be morphological barriers and physiological factors such as a wide range of pH and enzymatic activities. The lower water content and fluid mobility of the colon, which leads to longer retention times and also lower proteolytic activity of colon compared to other areas of the gastrointestinal tract, make the colon an ideal site for both systemic and local delivery of drugs. Therefore aggressive research efforts have recently focused on development of new strategies for delivering drugs to the colon. As a drug delivery systems, hydrogels have received increasing attention due to their outstanding merits. Among the various hydrogels, including natural, synthetic and natural/synthetic hybrid hydrogels, chitosan has attracted significant attention in a broad range of pharmaceutical and biomedical applications. Chitosan is a hydrophilic polyelectrolyte heteropolysaccharide composed of randomly (1→4)-linked 2- acetamido-2-deoxy-β-D-glucopyranose and 2-amino-2-deoxy-β-D-glucopyranose linked by (1→4)-β-glycosidic bonds. Unlike most known bioadhesive polymers, chitosan displays unique pharmaceutical and biomedical applications due to the large number of hydroxy and amino groups on the backbone of chitosan. These functional groups can be readily modified. This study was commenced with the aim of engineering a carrier with high enough physicochemical stability to reach the colon and to be able to protect a drug from various obstacles throughout the gastrointestinal tract. In this study, a new generation of chitosan derivatives was developed. Furthermore, their viability was investigated for potential applications as drug carriers to the colon. Chitosan based films with improved physical properties from introducing a cyclic imide moiety into the chitosan matrices was developed and characterised. Mechanical, thermal and chemical analyses of these films show that the heterocyclic imide linkage imparts excellent thermal, mechanical and chemical stability to the chitosan film. Additionally, spray dried chitosan microspheres with improved mechanical stability were examined for the controlled drug release of bovine serum albumin as a model protein drug. Additionally, a novel generation of amphoteric crosslinked chitosan derivatives was designed to be pH sensitive and bacterially degradable. Tabletted carriers were designed to protect the drug from the harsh acidic environment of the stomach and the rigorous enzymic activity of the small intestine and deliver the drug to the colon. Tabletted formulation forms of these novel amphoteric derivatives of chitosan showed the excellent potential formulations as colon specific drug delivery vehicles.